The present invention relates to a brake device for children's vehicle, and particularly to a brake improvement which overcomes the drawbacks of a conventional brake device that causes different braking force when the wheel rotating in different directions.
A conventional brake device for a motorized children's vehicle is shown in FIG. 1 in which a brake drum 12 and a brake band 14 are shown. The working condition of the brake device is further illustrated in FIG. 2 for depiction of its problem during working.
As shown in FIG. 1, a conventional brake device for a motorized children's vehicle includes a C-shaped brake band 14 surrounding a brake drum 12 which is coaxially formed with the wheel 10. Generally, the brake band 14 and the brake drum 12 of a motorized children's vehicle are made of stiff plastics. By fastening the brake band 14 on the brake disc 12, the wheel 10 can be braked. In the motorized children's vehicle, two rear wheels 10 are driven individually by two unshown driving mechanisms 20 for moving the vehicle forwards and backwards. The brake drum 12 rotating along with the wheel 10 will be braked when the brake band 14 is fastened to provide friction force to the brake drum 12.
The C-shaped brake band 14 surrounds a circular groove furnished on the brake drum 12, and is fixedly mounted on the driving mechanism 20 or the frame of the vehicle through a pivot 16. A pulling wire 24 has one end coming through two parallel ends of the C-shaped brake band 14, and the other end linking to an unshown brake pedal or handle. An adjuster 26 having an expansion spring 23 and a screw 28 is used to adjust the tension and stroke of the pulling wire 24. When the wire 24 is pulled by the brake pedal or handle, the brake band 14 then fastens the brake drum 12, i.e. the wheel 10, based on the pivot 16.
The wheel 10 may rotates forwards or backwards, i.e. the brake drum 12 rotates clockwise or counterclockwise, as shown in FIG. 2. The force direction of the pulling wire 24 when fastening the brake band 14 to the brake drum 12 is always in the direction as shown by the dashed (clockwise) arrow. When the brake drum 12, i.e. the wheel 10, rotates clockwise as same as the fastening direction of the brake band 14, the friction force of the brake band 14 to the brake drum 12 will enhance the fastening force and make an effective brake. But when the brake drum 12, i.e. the wheel 10, rotates counterclockwise and reversely to the fastening direction of the brake band 14, the friction force of the brake band 14 to the brake drum 12 will counter the fastening force, loosen the brake band 14 from the brake drum 12 and decrease the brake performance. From the aforesaid description, we know that the brake force of a conventional brake device for a motorized children's vehicle will vary when the wheel rotates forwards or backwards and will cause a problem.